The manufacture of an integrated circuit (IC) has been largely driven by the need to reduce the size of a semiconductor device and to increase the density of the integrated circuit in the semiconductor device. Wire bonding connects the semiconductor device to the packaging substrate. When the size of the semiconductor device shrinks, IC packaging process also needs to be improved to decrease the package size. However, the bond wiring requires additional space for IC packaging and may results in signal delay in the application of high-speed semiconductor devices.
A packaging method for packaging smaller semiconductor devices is known as wafer level packaging (WLP), in which integrated circuit dies are packaged together. Redistribution layer (RDL) is formed over interconnect structures of the integrated circuit dies to rewire and reposition external terminals at desired positions. The RDL included in the WLP is also to fan out wirings for contact pads of the respective integrated circuit die so that electrical contact can be made at a larger pitch than that of contact pads of the die.